The activity of two individual neurons in the somatosensory cortex of the cat were recorded simultaneously with the cortial surface waves. The distance between the two neurons was less than 0.5 mm. It was found that their spontaneous discharge patterns as a function of time and their responses to stimulation of a peripheral nerve or of the nucleus centrum medianum of the thalamus were different. With the cortex under the effect of strychnine, these neurons became epileptic and their epileptic discharges were not necessarily synchronous. Most of the cells underwent a prolonged depolarization for 100-680 msec with a magnitude of 20-50 mV. In these instances, there was no post-excitatory hyperpolarization suggesting that inhibitory impulses generated from the internuncial cells in the cortex are blocked and that the large and prolonged depolarization of the epileptic neuron is a result of the invasion of "unrestrained" excitatory synaptic impulses. During the period of prolonged depolarization, intracellular stimulation with depolarizing or hyperpolarizing pulses were applied. This did not change the time course of the prolonged depolarization although the intracellular stimulation altered the discharged frequency of the cell.